A number of chronic diseases in humans occur predominantly in individuals who have inherited particular HLA alleles, and among these diseases, psoriasis vulgaris exhibits the strongest association with Cw6. Our objective is to investigate the in vivo role of Cw6 in the pathomechanism of psoriasis. We have recently developed transgenic technology and produced rats expressing the transgenic HLA-B27; these animals exhibit inflammatory changes in several organs, including occasional psoriasiform skin changes. We thus hypothesize that Cw6 transgenic rats may consistently produce a spectrum of psoriatic changes, thereby serving as an animal model for this disease. Specific aims are: l) to produce transgenic rats expressing a functional HLA-Cw6 gene, or HLA-Cw3 gene (as a control), 2) to observe transgenic rats for evidence of psoriasiform skin disease, and 3) to examine the functional role of the Cw6 transgene product in disease development. These studies should provide basic knowledge for understanding pathomechanisms of psoriasis and would offer a useful model for developing novel therapeutic protocols.